Inspection Procedure 19: The FCM cannot be turned on or off when the FCM ON/OFF switch is operated.


caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
  • Before replacing the ECU, ensure that the communication circuit is normal.

COMMENTS ON TROUBLE SYMPTOM

  • The ACC/FCM-ECU has detected an abnormality.
  • The FCM ON/OFF switch circuit is short-circuited.

PROBABLE CAUSES

  • Damaged wiring harness and connectors
  • Malfunction of FCM ON/OFF switch
  • Malfunction of ETACS-ECU
  • Malfunction of ACC/FCM-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 2
Repair the CAN bus lines. (Refer to GROUP 54C - CAN Bus Diagnostics Table .)

STEP 2. M.U.T.-III diagnosis code
Use M.U.T.-III to check the diagnosis code for the ACC/FCM system (Refer to ).

Q. Is the diagnosis code set?
Carry out the diagnosis for the diagnosis code (Refer to ).
Go to Step 3

STEP 3. M.U.T.-III data list for other system
Check the ETACS-ECU system data list.

  • Press the FCM ON/OFF switch.
Item No.
 Item name
 Normal condition
404
 FCM switch
 ON (the switch being pressed)

Q. Is the check result normal?
Go to Step 8
Go to Step 4

STEP 4. FCM ON/OFF switch check
Refer to .

Q. Is the check result normal?
Go to Step 5
Replace the FCM ON/OFF switch.

STEP 5. Resistance measurement at FCM ON/OFF switch connector.
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Measure the resistance between the FCM ON/OFF switch connector (earth terminal) and the body earth.
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?
Go to Step 7
Go to Step 6

STEP 6. Check of open circuit in earth line between FCM ON/OFF switch connector and the body earth

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunction ).
Repair the connector(s) or wiring harness.

STEP 7. Check of open circuit in FCMS line between ETACS-ECU connector and FCM ON/OFF switch connector

Q. Is the check result normal?
Replace the ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ).
Repair the connector(s) or wiring harness.

STEP 8. M.U.T.-III data list
Check the ACC/FCM system data list.

  • Press the FCM ON/OFF switch.
Item No.
 Item name
 Normal condition
404
 FCM switch state
 ON (the switch being pressed)

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunction ).
Replace the ACC/FCM-ECU (Refer to GROUP 17 - Adaptive Cruise Control System (ACC) ).